Conveyor system

ABSTRACT

A conveyor system is disclosed for transporting workpieces. The conveyor system includes an elongated frame having an inlet end and an outlet end. A pair of sprockets are rotatably mounted to both the inlet end and outlet end while a pair of closed loop chains are mounted around the sprockets so that the chains are spaced apart and parallel to each other along the frame. A motor rotatably drives the sprockets and thus the chains along the frame. A plurality of pallets, each adapted to support a workpiece, are slidably mounted to the chains by rollers so that the pallets can move longitudinally with respect to the chains. A cam is secured to the sprockets at both the inlet and outlet ends of the conveyor frame. These cams engage a cam follower on the pallet to raise the pallets from a lower section of the chain to an upper section at the inlet end of the conveyor frame and vice versa at the outlet end of the conveyor frame.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates generally to conveyor systems and, moreparticularly, to an accumulating conveyor system.

II. Description of the Prior Art

There are many previously known conveyor systems for transporting partsalong an elongated conveyor frame. Many of these conveyors systems,furthermore, are known as accumulating conveyor systems in which theworkpieces transported by the conveyor system can remain stationarydespite continued operation of the conveyor system. Furthermore, many ofthese previously known conveyor systems utilize pallets mounted to theconveyor system for transporting the parts.

These previously known conveyor systems, however, have suffered from anumber of disadvantages. These previously known accumulating conveyorsystems often utilize pallets to transport workpieces from the inlet endof the conveyor frame and to the outlet end of the conveyor frame. Afterthe workpiece has been transported to the outlet end and removed fromits pallet, the pallet must be returned to the inlet end of the conveyorsystem whereupon the process is repeated.

These previously known conveyor systems have utilized complicatedmechanisms for returning the workpiece carrying pallet to the inlet endof the conveyor system. Because of the complexity of such systems, thesepreviously known conveyor systems have been known to jam, break down,and are subject to excessive wear of the parts. Such excessive wearnecessitates frequent maintenance and/or replacement of the entireconveyor system.

SUMMARY OF THE PRESENT INVENTION

The present invention provides a conveyor system which overcomes all ofthe above mentioned disadvantages of the previously known systems.

In brief, the conveyor system of the present invention comprises anelongated frame having a pair of sprockets mounted at both its inlet endand its outlet end. A pair of closed loop chains are mounted to thesprockets so that the chains are spaced apart and parallel to eachother. In doing so, the chains form an upper conveyor section extendingfrom the inlet end of the conveyor frame to the outlet end, and a lowerconveyor section extending beneath the upper section.

A motor is then employed to rotatably drive the conveyor chains so thatthe upper section of the conveyor chains moves from the inlet end of theconveyor frame towards the outlet end while the lower section of theconveyor chains moves in the opposite direction.

At least one, and preferably several pallets are slidably mounted byrollers to the chains so that the pallets can remain stationary despitecontinued longitudinal movement of the chains. Each pallet includesmeans for supporting a workpiece above the pallets.

In order to lower the pallets from the upper section of the chain to thelower section at the outlet end of the conveyor frame, and vice versa atthe inlet end of the conveyor frame, each pallet includes a camfollower. This cam follower cooperates with a cam mounted to each set ofsprockets so that, when the cam follower enters into the cam, the camand cam follower move in unison with each other. Thus, at the inlet endof the conveyor, the cooperation between the cam and cam followerengages the pallet and raises the pallet from the lower section of thechain to the upper section. Similarly, at the outlet end of the conveyorframe, the cooperation between the cam follower and the cam lowers thepallet from the upper section of chain to the lower section for returnto the inlet end of the conveyor frame.

In the preferred embodiment of the invention, each cam comprises a diskhaving a cut out while the cam follower comprises a roller whichregisters with and is received within the disk cut out. A stop member oneach pallet abuts against the disk, until the stop member registers withthe cut out, to synchronize the cam followers on the pallets with thereceiving cut outs on the cams.

BRIEF DESCRIPTION OF THE DRAWING

A better understanding of the present invention will be had uponreference to the following detailed description, when read inconjunction with the accompanying drawing, wherein like referencecharacters refer to like parts throughout the several views, and inwhich:

FIG. 1 is a side view illustrating a preferred embodiment of the presentinvention;

FIG. 2 is a section view taken substantially along line 2--2 in FIG. 1and enlarged for clarity;

FIG. 3 is a view of circle 3--3 in FIG. 2 and enlarged for clarity;

FIG. 4 is an exploded fragmentary view illustrating the operation of thepreferred embodiment of the invention;

FIG. 5 is a view taken substantially along arrow 5--5 in FIG. 4;

FIGS. 6-9 are diagrammatic views similar to FIG. 5 and illustrating theoperation of the present invention;

FIG. 10 is a view taken along arrow 10--10 in FIG. 6; and

FIG. 11 is a cross sectional view illustrating one side of the conveyorframe and illustrating a modification thereof.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION

With reference first to FIGS. 1-3, a preferred embodiment of theconveyor system 10 of the present invention is thereshown and comprisesan elongated frame 12 having an inlet end 14 and an outlet end 16. In amanner which will be subsequently described in greater detail, theconveyor system 10 transports parts or workpieces 18 from the inlet end14 and to the outlet end 16 of the frame 12.

A pair of closed loop chains 20 and 22 (FIG. 2) are rotatably mounted bysprockets 24 to the inlet end 14 and by sprockets 26 (FIG. 1) to theoutlet end 16 of the frame 12. The inlet sprockets 24 are mounted to acommon axle 28 (FIG. 2) while similarly, the outlet sprockets 26 aremounted to a common axle 30 (FIG. 1) so that the sprockets 24 and 30 allrotate in unison with each other. Furthermore, as best shown in FIG. 2,the chains 20 and 22 are spaced apart and generally parallel to eachother. As best shown in FIG. 1, the chains 20 and 22 are each a closedloop thus forming an upper conveyor section 32 and a lower conveyorsection 34.

Referring now to FIG. 1, a motor 36 is used to rotatably drive thesprockets 26. Thus, in doing so, the sprockets 26 drive the chains 20and 22 in unison with each other so that the upper conveyor section 32moves from the inlet end 14 of the frame 12 towards the outlet end 16while, conversely, the lower conveyor section 34 moves from the outletend 16 of the frame 12 towards the inlet end 14.

Referring again to FIGS. 1-3, in order to support the chains 20 and 22between the ends 14 and 16 of the frame 12, a slide block 38 is mountedbetween a portion of the frame 12 and each chain 20 and 22 along theentire length of both the upper section 32 and the lower section 34.Preferably, the slide blocks 38 are an oil impregnated syntheticmaterial so that friction is minimized between the chains 20 and 22 andthe frame 12.

As shown in FIG. 1, the conveyor system 10 includes at least one, andpreferably a plurality, of pallets 40 for transporting the workpieces 18from the inlet end 14 and to the outlet end 16 of the frame 12 asdepicted by arrow 42. After reaching the outlet 16 of the frame 12, andthe workpiece 18 removed from the pallet 40, as depicted at 44, thepallets 40 are returned to the inlet end 14 along the lower conveyorsection 34.

With reference now especially to FIG. 4, the pallet 40 is thereshown ingreater detail and comprises a base 50 having work support members 52extending upwardly from the upper side of the base 50. These members 52are specially fabricated to support the particular workpiece 18(illustrated in FIG. 2 as a crankshaft), although other parts can, ofcourse, be transported.

Referring now especially to FIGS. 3 and 4, a pair of upper rollers 54are provided along each lateral side of the pallet base 50. Theserollers 54, as best shown in FIG. 3, engage the top of the chains 20 and22 along the upper conveyor section 32 of the chains. The rollers 54 arepreferably ball bearing rollers so that the rollers 54 slidably mountthe pallet 40 to the chains 20 and 22. Thus, the pallet 40 can remainstationary despite continued movement of the chains 20 and 22 thereforepermitting accumulation of the pallets 40 along the conveyor system 10.

Referring now to FIGS. 1 and 4, a lower roller 56 is also rotatablymounted to each lateral side of the pallet base 50. This lower roller 56is positioned below the chains 20 and 22 along the upper section 32 ofthe chain (FIG. 3). However, when the pallets 40 are inverted, as shownat 46 in FIG. 1, for their return from the outlet end 16 to the inletend 14 of the frame 12, the lower rollers 56 support the pallet 40 alongthe top of the chains 22 and 24 along the lower conveyor section 34.Thus, relative movement of the pallets 40 with respect to the chains isaccomplished both along the upper conveyor section 32 and lower conveyorsection 34 thus permitting the pallets 40 to accumulate along both chainsections 32 and 34.

Referring again to FIGS. 3 and 4, a plurality of guide rollers 58 arealso rotatably mounted to the pallet along an axis perpendicular to thelongitudinal axis of the chains 20 and 22. These guide rollers 58 canabut against the opposite sides of the frame 12, or slide blocks 38(FIG. 3) to minimize friction between the pallets 40 and the sides ofthe frame 12.

As shown in FIG. 4, the pallets preferably include one or more bumpers60 which cushion any impact between adjacent pallets 40.

A stop member 62 is also attached to each lateral side of the pallet 40.The operation and purpose of the stop block will be described below.

The operation of moving the pallets 40 between the upper section 32 andlower section 34 of the chains will now be described for lowering thepallets 40 from the upper conveyor section 32 to the lower conveyorsection 34 at the outlet end 16 of the conveyor frame 12. It will beunderstood, however, that a like description shall also apply forraising the pallets 40 from the lower section 34 to the upper section 32at the inlet end 14 of the conveyor frame 12.

With reference then to FIGS. 4 and 5, a cam 70 is mounted adjacent eachsprocket 26 at the outlet end 16 of the conveyor frame. These cams 70are generally disk shaped but include a generally V-shaped cut out 72.The cut outs 72 face each other and the cams 70 are secured to thesprockets 26 so that the cams 70 together with their cut outs 72 rotatein unison with the sprockets 26.

With reference now especially to FIG. 5, as the pallet 40 approaches thecam 72, the stop member 62 on the pallet 40 registers with an outerperiphery 74 of the cam 70. Thus, with the stop member 62 in abutmentwith the outer periphery 74 of the cam 70, the stop member 62 holds thepallet 40 stationary until the stop member 62 registers with the cut out72. When this occurs, the stop member 62 moves into the cut out as shownin FIG. 6.

With reference then to FIG. 6, as the stop member registers with the camcut out 72, both the stop member 62, together with the lower roller 56moves into the cam cut out 72. The lower roller 56 on the pallet forms acam follower for the cam 70.

With reference now to FIGS. 7-9, with the roller or cam follower 56positioned in the cam cut out 72, the continued rotation of the sprocket26 rotatably drives the roller 56, together with its attached pallet 40from the upper position, illustrated in FIG. 6, through the positionshown sequentially in FIGS. 7 and 8 and to the lower position as shownin FIG. 9. Furthermore, as shown in FIG. 9, in its lower position thesprocket 26 releases the cam follower or roller 56 to the lower conveyorsection 34. The pallet 40 is then transported back to the inlet end 14of the frame 12 due to the friction between the roller 56 and the chains20 and 22. However, as previously described, the pallets 40 canaccumulate along the lower chain section 34 which simply results inrotation of the rollers 56 with respect to their respective chains 20and 22.

As best shown in FIGS. 6 and 10, the cam cut out 72 has a steppedconstruction with the outermost step 75 engaging the cam follower orroller 56 and the innermost step 76 in registration with the stop member56. This step construction minimizes rubbing between the stop member 56and the cam 70 during operation of the conveyor system 10.

Substantially identical cams are secured to the sprockets 24 at theinlet end 14 of the conveyor frame 12. Thus, the operation of thesecams, together with the cam followers or rollers 56, is substantiallyidentical to that depicted in FIGS. 5-6, in an inverted position.Therefore, a further description is unnecessary.

With reference now to FIG. 11, an alternate, and indeed preferred,construction of the frame is thereshown in cross section. Preferably,each side of the frame 12 is constructed from two F-shaped extrusions 80for inexpensive and yet durable construction. The extrusions 80 may alsoinclude one or more T-slots 82 for attachment of machining fixtures,gauges or the like.

In operation of the conveyor system, the chains 20 and 22 arecontinuously driven by the motor 36. Workpieces are loaded onto thepallets 40 adjacent the inlet end of the conveyor frame 12 and areunloaded by conventional means at the outlet end 16 of the conveyorframe 12. As previously described, the pallets 40 are continuouslyrecirculated between the inlet and outlet ends 14 and 16 of the frame12.

Although each of the pallets 40 is slidably mounted to the chains 20 and22 by the rollers 54 and 56, the friction between the rollers 54 and 56and the chains 22 and 24, together with internal friction of the rollers56 causes the pallets 40 to move in synchronism with the chains 22 and24. However, the pallets 40 can accumulate, i.e. remain stationary,along either the upper section 32 or lower section 34 of the chains 22and 24 when necessary whereupon the rollers 54 or 56 rotate and allowrelative movement between the pallets 40 and the chains 20 and 22.

Furthermore, although the present invention has been described simplyfor moving parts from the inlet end 14 and to the outlet end 16 of theconveyor, machining operations on the workpieces 18 along the conveyorsystem 10 are, of course, possible. In such a situation, the pallet 40would be locked at a predetermined position along the conveyor system,e.g. by raising the pallet 40 into a fixture at a predetermined positionalong the conveyor system. When raised into the fixture, the palletwould remain stationary at a predetermined location whereupon machiningoperations are possible.

From the foregoing, it can be seen that the present invention provides aconveyor system that is highly effective in operation and yet exhibitsonly minimal wear and tear on the moving systems of the conveyor. Havingdescribed my invention, however, many modifications thereto will becomeapparent to those skilled in the art to which it pertains withoutdeviation from the spirit of the invention as defined by the scope ofthe appended claims.

I claim:
 1. A conveyor system for transporting workpieces comprisinganelongated frame having an inlet end and an outlet end, an endless memberforming a closed loop, means for rotatably mounting said endless memberto said inlet and said outlet ends of said frame so that said endlessmember forms both an upper and a lower section extending between saidends of said frame, means for driving said endless member so that saidupper section moves from said inlet end towards said outlet end and sothat said lower section simultaneously moves from said outlet endtowards said inlet end, at least one pallet adapted to support theworkpiece, means for slidably mounting said pallet to said endlessmember so that said pallet can move relative to said endless member,means at said inlet end of said frame for lifting said pallet from saidlower section to said upper section of said endless member, and means atsaid outlet end of said frame for lowering said pallet from said uppersection to said lower section of said endless member, wherein said meansfor slidably mounting said pallet to said endless member comprises atleast an upper roller and a lower roller, said rollers being rotatablymounted to said pallet, said rollers being positioned on opposite sidesof said endless member.
 2. The invention as defined in claim 1 whereinsaid pallet includes a cam follower and wherein said lifting meanscomprises a cam attached to said rotatable mounting means at said inletend of said frame, said cam engaging said cam follower and elevatingsaid pallet from said lower section to said upper section duringrotation of said rotatable mounting means.
 3. The invention as definedin claim 2 wherein said cam comprises a disk coaxially secured to saidrotatable mounting means, said disk having a cut out, said cam followerentering into said cut out when said cam follower registers with saidcut out whereupon said cam and said cam follower rotate in unison witheach other.
 4. The invention as defined in claim 3 and comprising a stopblock on said pallet which abuts against said cam and prevents movementof said pallet until said cam follower registers with said cam.
 5. Theinvention as defined in claim 1 wherein said pallet includes a camfollower and wherein said lowering means comprises a cam attached tosaid rotatable mounting means at said outlet end of said frame, said camengaging said cam follower and lowering said pallet from said uppersection to said lower section during rotation of said rotatable mountingmeans.
 6. The invention as defined in claim 5 wherein said cam comprisesa disk coaxially secured to said rotatable mounting means, said diskhaving a cut out, said cam follower entering into said cut out when saidcam follower registers with said cut out whereupon said cam and said camfollower rotate in unison with each other.
 7. The invention as definedin claim 6 and comprising a stop block on said pallet which abutsagainst said cam and prevents movement of said pallet until said camfollower registers with said cam cut out.
 8. The invention as defined inclaim 1 wherein said endless member comprises a chain and said rotatablemounting means comprises a sprocket.
 9. The invention as defined inclaim 8 wherein said means for moving said endless member comprisesmeans for rotatably driving said sprocket.
 10. The invention as definedin claim 1 wherein said endless member comprises a pair of chains, eachforming a closed loop, said chains being spaced apart and parallel toeach other.
 11. The invention as defined in claim 1 wherein said rollersare spaced apart from each other by a distance greater than a thicknessof said endless member so that only said upper roller engages saidendless member on said upper section while only said lower rollerengages said endless member on said lower section of said endlessmember.
 12. The invention as defined in claim 11 wherein said at leastone upper roller comprises a pair of longitudinally spaced rollers. 13.The invention as defined in claim 2 wherein a portion of said endlessmember overlies said cam.
 14. The invention as defined in claim 1 andcomprising means for slidably mounting said endless member to said framebetween the inlet and outlet ends of said frame.
 15. A conveyor systemfor transporting workpieces comprisingan elongated frame having an inletend and an outlet end, an endless member forming a closed loop, meansfor rotatably mounting said endless member to said inlet and said outletends of said frame so that said endless member forms both an upper and alower section extending between said ends of said frame, means fordriving said endless member so that said upper section moves from saidinlet end towards said outlet end and so that said lower sectionsimultaneously moves from said outlet end towards said inlet end, atleast one pallet adapted to support the workpiece, means for slidablymounting said pallet to said endless member so that said pallet can moverelative to said endless member, means at said inlet end of said framefor lifting said pallet from said lower section to said upper section ofsaid endless member, and means at said outlet end of said frame forlowering said pallet from said upper section to said lower section ofsaid endless member, wherein said pallet includes a cam follower andwherein said lifting means comprises a cam attached to said rotatablemounting means at said inlet end of said frame, said cam engaging saidcam follower and elevating said pallet from said lower section to saidupper section during rotation of said rotatable mounting means, whereinsaid cam comprises a disk coaxially secured to said rotatable mountingmeans, said disk having a cut out, said cam follower entering into saidcut out when said cam follower registers with said cut out whereuponsaid cam and said cam follower rotate in unison with each other, a stopblock on said pallet which abuts against said cam and prevents movementof said pallet until said cam follower registers with said cam.
 16. Aconveyor system for transporting workpieces comprisingan elongated framehaving an inlet end and an outlet end, an endless member forming aclosed loop, means for rotatably mounting said endless member to saidinlet and said outlet ends of said frame so that said endless memberforms both an upper and a lower section extending between said ends ofsaid frame, means for driving said endless member so that said uppersection moves from said inlet end towards said outlet end and so thatsaid lower section simultaneously moves from said outlet end towardssaid inlet end, at least one pallet adapted to support the workpiece,means for slidably mounting said pallet to said endless member so thatsaid pallet can move relative to said endless member, means at saidinlet end of said frame for lifting said pallet from said lower sectionto said upper section of said endless member, means at said outlet endof said frame for lowering said pallet from said upper section to saidlower section of said endless member, wherein said pallet includes a camfollower and wherein said lowering means comprises a cam attached tosaid rotatable mounting means at said outlet end of said frame, said camengaging said cam follower and lowering said pallet from said uppersection to said lower section during rotation of said rotatable mountingmeans, wherein said cam comprises a disk coaxially secured to saidrotatable mounting means, said disk having a cut out, said cam followerentering into said cut out when said cam follower registers with saidcut out whereupon said cam and said cam follower rotate in unison witheach other, and a stop block on said pallet which abuts against said camand prevents movement of said pallet until said cam follower registerswith said cam cut out.